We showed in a paper published in Science today that feedback between soil biota and plants of contrasting nutrient-acquisition-strategies contributes to the maintenance of high plants species and functional diversity in Mediterranean-climate shrublands. The paper is available here.

It is a great honour to have been awarded the 2016 Tansley Medal from the New Phytologist Trust. The invited review that was judged during the competition is available here.

Etienne Lalibertéetiennelaliberte@elaliberte.info2016tansleymedal1https://sites.google.com/feeds/content/elaliberte.info/www/90041505068345272152016-12-08T15:38:04.220Z2016-12-08T15:38:04.223Z2016-12-08T15:38:04.217ZPlant-soil feedback and the maintenance of diversity

Our study on the role of plant-soil feedback for the maintenance of plant diversity in hyperdiverse Australian scrublands was recently accepted for publication in Science. Stay tuned!

Native pathogens reduce plant competition

Felipe Albornoz, a recent PhD graduate in our lab, has published a video blog post on here explaining the results of his recent study in Journal of Ecology. Worth watching -- only 7 min long and very well made!

Plant species show a remarkable diversity of belowground strategies to acquire nutrients: different types of mycorrhizal associations, symbioses with nitrogen-fixing bacteria, and many more. While most plant species use only one strategy, a few plant species possess the ability to form different types of symbiotic associations with some fungi and bacteria.

Felipe Albornoz (PhD student) studied two plant species in south-western Australia that occur across a long-term soil chronosequence representing a very strong soil nutrient availability gradient. These two plant species can form arbuscular or ectomycorrhizal association, and one also fixes nitrogen in root nodules with the help of some bacteria. The results showed that plant investment into these different associations depends on soil nutrient availability, particularly which nutrient (nitrogen or phosphorus) limits plant growth. Arbuscular mycorrhizal colonisation was higher in younger, more P-rich soils but shifted toward ectomycorrhizal colonisation in older P-poor soils where most of the P is in organic forms. Investment in N-fixing nodules declined with soil age because P rather than N became the limiting nutrient.

This study was just published in Ecology and Evolution. See publications for more details.

Mycorrhizal fungi are root symbionts of plants, and their main benefit to plants is thought to enhance the acquisition of soil phosophorus. However, when soils become extremely old and phosphorus-impoverished, it seems that the mycorrhizal strategy becomes ineffective. Our new study shows that extraradical mycorrhizal hyphal biomass is indeed extremely low in old, phosphorus-impoverished soils. This suggests that plants reduce carbon allocation to mycorrhizal fungi when phosphorus becomes extremely low, or that mycorrhizal fungi struggle to acquire the phosphorus they need for their own growth.

We published this new article in Soil Biology and Biochemistry. It can be downloaded from this page.

A new study has been accepted for publication in Molecular Ecology. In this study, we used pyrosequencing to survey shifts in arbuscular mycorrhizal (AM) fungal communities on roots and in soils along the retrogressive part of the 2-million year Jurien Bay dune chronosequence in south-western Australia.

Surprisingly, we found that AM fungal diversity initially increased from 1000-year old soils (quite fertile) to 120,000-year soils (low in phosphorus), but that diversity then declined markedly on 2,000,000 years with extremely low phosphorus availability. This suggests environmental filtering of AM fungi during ecosystem retrogression, when phosphorus reaches extremely low levels.

Etienne Lalibertéetiennelaliberte@elaliberte.infoarbuscularmycorrhizalfungaldiversityrisesbutthenfallsduringecosystemretrogression1https://sites.google.com/feeds/content/elaliberte.info/www/52802457953463900022015-03-13T17:19:51.015Z2015-03-13T17:19:51.019Z2015-03-13T17:19:51.010ZPlant nutrient acquisition: more than one way to skin a cat in infertile soils

PhD student Graham Zemunik has just had the first chapter of this thesis accepted in the new journal Nature Plants. Congratulations Graham! Graham's study shows that the diversity of plant-nutrient acquisition strategies (i.e. different types of mycorrhizal association, ability to fix N, non-mycorrhizal types, carnivory, parasitism, etc) increases as soils get progressively more nutrient-imporverished during long-term soil development. Moreover, mycorrhizal plants are more abundant in young, relatively fertile soils but because progressively less abundant with declining fertility (especially P availability), while non-mycorrhizal plant species increase in abundance.

Patrick Hayes (former Honours student) published his thesis results in Journal of Ecology. His thesis quantified changes in foliar nutrient concentrations and resorption of native plant species along the Jurien Bay dune chronosequence. We found a sharp decline in foliar P concentrations and increase in P resorption with increasing soil age (and declining P availability). We also found that N-resorption efficiency was greatest in the youngest soil, which was previously linked with N limitation. This study provides additional support for shifts from N to P limitation of plant growth along the 2-million year Jurien Bay chronosequence.

A new special feature on plant-soil feedback has just been published in Journal of Ecology. With Paul Kardol (lead author), we wrote one of the articles. The article reviews temporal aspects of plant-soil feedback. One of the conclusions is that more work is needed to understand how long-term changes in abiotic conditions (e.g. changes in soil nutrient availability during long-term pedogenesis) can influence the strength and direction of plant-soil feedback. It is not a coincidence that this is one of our current research projects.

We wrote a review that presents different hypotheses to explain why older, more strongly-weathered soils generally show greater plant diversity. This review has just been accepted in Trends in Ecology and Evolution. In our paper, we propose that long-term soil chronosequences will be excellent 'natural experiments' to further advance our understanding of belowground controls over plant diversity, and suggesting a methodological approaches that should allow us to evaluate the relative importance of different factors.

A study exploring how plant functional diversity changes with long-term shifts in soil resource availability and grazing intensity in New Zealand grasslands has just been published in Journal of Vegetation Science. This article was invited for a special feature on plant functional diversity. It shows that two both functional trait converegence and divergence occur in plant communities, but operate at different spatial scales.

Etienne Lalibertéetiennelaliberte@elaliberte.infonewarticleinjournalofvegetationscience1https://sites.google.com/feeds/content/elaliberte.info/www/94179259727010062013-01-22T00:50:10.360Z2013-01-22T00:50:10.363Z2013-01-22T00:50:10.356ZWelcome to Felipe and Kenny

Two new PhD students joined the group in the last few months: Felipe Albornoz, who will work on plant interactions along soil nutrient availability gradients, and Kenny Png, who will work on nitrogen fixation during long-term soil development. Both have been able to secure their own PhD scholarships; congratulations!

We just had a paper published that explores the use of nonlinear beta regression for estimating litter decomposition rates in single-pool models. Our initial hypothesis was that beta regression would be better suited to litter decomposition rate estimation because of the bounded nature of proportional litter mass loss data, and because of reduced variance near bounds. However, we found that nonlinear normal regression was actually quite good, despite its assumptions being violated. The beta model, however, should still be useful.

We have a new paper published in Oecologia that provides a long-term test of Michael Huston's 1979 dynamic equilibrium model of plant species diversity, using a 27-year fertilisation x grazing intensity trial in New Zealand (my PhD study).

Etienne Lalibertéetiennelaliberte@elaliberte.infodynamicequilibriummodelnewpaperinoecologia1https://sites.google.com/feeds/content/elaliberte.info/www/60439691769193721022012-07-20T10:44:44.924Z2012-07-20T10:45:14.241Z2012-07-20T10:45:13.273ZPaper accepted in New Phytologist

Our new paper, just accepted in New Phytologist, showed that P-efficient Proteaceae from P-impoverished soils in south-western Australia replace a large amount of their phospholipids with galacto- and sulfolipids as leaves develop. This probably helps to explain why they can have such high P-photosynthetic use efficiency.

We have a new paper now in press in Annals of Botany that describes the process of phosphorus-mobilisation ecosystem engineering in young soils that are rich in phosphorus (P), but where P is strongly sorbed (and thus not easily available).

Plants that release large amounts of carboxylates to mobilise this large but not easily-available pool of P make P accessible to neighbouring plants that do have have specialised strategies to access sorbed P.

A new paper by myself and Jason Tylianakis has just been published in the 01/2012 issue of Ecology. This paper explore the direct and indirect links between long-term fertilisation, grazing intensity, plant traits and ecosystem functioning. It was one of the key papers of my PhD.

It shows, among other things, that (i) the effect of herbivores on plant functional diversity depends on soil resource availability, (ii) the effect of herbivores and plant functional diversity on NPP is negative at low fertility but positive at high fertility, and (iii) NPP is a central integrator of ecosystem functioning.

Ecosystem progression and retrogression are considered to be causally linked to shifts from nitrogen to phosphorus limitation, but evidence to support this view remains scarce. We conducted a nutrient-limitation bioassay along a 2-million year dune chronosequence in Australia and provide strong experimental evidence in support of this view. This study is now accepted for publication in Journal of Ecology.

Congratulations to Graham, who won a competitive Australian Endeavour Award! This generous award will allow Graham to complete a >6-month research project at Unicamp, Campinas, Brasil, under the supervision of Prof Rafael Silva Oliveira. This project will explore nutrient-uptake strategies of native plants of highly nutrient-impoverished Cerrado ecosystems, and will be a central part of Graham's PhD thesis.

I have just received a competitive ARC Discovery Earler Career Researcher Award (DECRA). This three-year fellowship will allow me to start my research programe focused on understanding mechanismis of plant species coexistence in megadiverse plant communities of south-western Australia. Thanks to the ARC for their support.